Plasma processing method and plasma processing apparatus

ABSTRACT

A method for processing a substrate includes: supplying a pulsed source RF signal to an antenna disposed above a chamber, the pulsed source RF signal including a plurality of source cycles each having a source operating state and a source non-operating state after the source operating period; and supplying a pulsed bias RF signal to a lower electrode disposed in a substrate support provided in the chamber, the pulsed bias RF signal including a plurality of bias cycles having a same pulse frequency as that of the plurality of source cycles, each bias cycle having a bias operating state during a bias operating period and a bias non-operating state during a bias non-operating period after the bias operating period. A transition timing to the bias operating state in each bias cycle is delayed with respect to a transition timing to the source operating state in a corresponding source cycle.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. application Ser.No. 17/313,180, filed on May 6, 2021, which claims priority fromJapanese Patent Application Nos. 2020-085140 and 2021-008470, filed onMay 14, 2020 and Jan. 22, 2021, respectively, with the Japan PatentOffice, all of which are incorporated herein in their entirety byreference, and priority is claimed to each of the foregoing.

TECHNICAL FIELD

The present disclosure relates to a plasma processing method and aplasma processing apparatus.

BACKGROUND

US Patent Laid-Open Publication No. 2017/0040174 discloses a technologyof pulsing a radio frequency (RF) signal in an apparatus usinginductively coupled plasma (ICP, also referred to as transformer coupledplasma (TCP)). US Patent Laid-Open Publication No. 2017/0040174discloses that, for example, a source RF signal supplied to a coil and abias RF signal supplied to a chuck are synchronized such that the pulsesequences are reversed.

SUMMARY

A method for processing a substrate by a plasma processing apparatus,the plasma processing apparatus including a chamber, a substrate supportdisposed in the chamber, a lower electrode disposed in the substratesupport, and an antenna disposed above the chamber, the methodcomprising: supplying a pulsed source RF signal to the antenna, thepulsed source RF signal including a plurality of source cycles, eachsource cycle having a source operating state during a source operatingperiod and a source non-operating state during a source non-operatingperiod after the source operating period; and supplying a pulsed bias RFsignal to the lower electrode, the pulsed bias RF signal including aplurality of bias cycles having a same pulse frequency as that of theplurality of source cycles, each bias cycle having a bias operatingstate during a bias operating period and a bias non-operating stateduring a bias non-operating period after the bias operating period,wherein a transition timing to the bias operating state in each biascycle is delayed with respect to a transition timing to the sourceoperating state in a corresponding source cycle, the sourcenon-operating period overlaps with the bias non-operating period, andthe bias operating period in each bias cycle overlaps with the sourceoperating period in a next source cycle.

The foregoing summary is illustrative only and is not intended to be inany way limiting. In addition to the illustrative aspects, embodiments,and features described above, further aspects, embodiments, and featureswill become apparent by reference to the drawings and the followingdetailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a conceptual view of a configuration of a plasma processingapparatus according to an embodiment.

FIG. 2 is a schematic vertical cross-sectional view illustrating anexample of the configuration of the plasma processing apparatus in FIG.1 .

FIG. 3 is a flowchart illustrating an example of a flow of a plasmaprocessing according to the embodiment.

FIGS. 4A to 4C are views illustrating an example of a substrateprocessed by the plasma processing according to the embodiment.

FIG. 5 is a view illustrating a waveform example of a radio frequency(RF) signal used for RF power supply in the plasma processing accordingto the embodiment.

FIGS. 6A to 6E are views for explaining changes of physical quantitiesin a plasma processing chamber according to Waveform Example 1 of an RFsignal.

FIGS. 7A to 7E are views for explaining changes of physical quantitiesin a plasma processing chamber according to Waveform Example 2 of an RFsignal.

FIGS. 8A to 8E are views for explaining changes of physical quantitiesin a plasma processing chamber according to Waveform Example 3 of an RFsignal.

FIGS. 9A to 9E are views for explaining changes of physical quantitiesin a plasma processing chamber according to Waveform Example 4 of an RFsignal.

FIG. 10 is a view illustrating a waveform example of an RF signal usedfor RF power supply in the plasma processing according to Modification1.

FIG. 11 is a view illustrating a waveform example of an RF signal usedfor RF power supply in the plasma processing according to Modification2.

FIG. 12 is a view illustrating a waveform example of an RF signal usedfor RF power supply in the plasma processing according to Modification3.

FIG. 13 is a view illustrating a waveform example of an RF signal usedfor RF power supply in the plasma processing according to Modification4.

FIG. 14 is a view illustrating a waveform example of an RF signal usedfor RF power supply in the plasma processing according to Modification5.

FIG. 15 is a flowchart illustrating an example of a flow of the RF powersupply of the plasma processing according to the embodiment.

FIG. 16 is a flowchart illustrating another example of a flow of the RFpower supply of the plasma processing according to the embodiment.

FIGS. 17A to 17C are views for explaining an example of a shapeabnormality that occurs in etching.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof. The illustrativeembodiments described in the detailed description, drawings, and claimsare not meant to be limiting. Other embodiments may be utilized, andother changes may be made without departing from the spirit or scope ofthe subject matter presented here.

Hereinafter, embodiments for implementing a plasma processing apparatusand a plasma processing method according to the present disclosure(hereinafter, referred to as “embodiments”) will be described in detailwith reference to the drawings. The present disclosure is not limited tothe embodiments. Further, the respective embodiments may beappropriately combined within a range that does not contradict theprocessing contents. Further, in the following respective embodiments,the same portions are denoted by the same reference numerals, andredundant description will be omitted.

Example of Shape Abnormality that Occurs in Etching

First, descriptions will be made on an example of a shape abnormalitythat occurs in etching of a silicon film before describing embodiments.FIGS. 17A to 17C are views for explaining the example of the shapeabnormality that occurs in the etching of the silicon film.

In recent years, a technology for processing a hole having a high aspectratio has attracted attention in a semiconductor manufacturingtechnology. As an example, there is high aspect ratio contact (HARC).HARC is used for a dynamic random access memory (DRAM) or athree-dimensional NAND. The aspect ratio of HARC used for DRAM is, forexample, 45, and the aspect ratio of HARC used for a three-dimensionalNAND exceeds 65.

As the aspect ratio of the hole to be formed increases, it becomesdifficult to form the hole straight in the vertical direction. Forexample, as illustrated in FIG. 17A, a phenomenon of tapering occurs asit approaches the vicinity of the bottom of the hole. The cause of thisphenomenon is considered that, for example, the incident direction ofions in plasma is oblique to the depth direction of the hole, and it isdifficult for the ions to be transported to the bottom portion of thehole. Further, it is considered that the ions stay in the holes anddisrupts the course of subsequent ions.

Further, as illustrated in FIG. 17B, substances scraped by etching orreaction products produced by plasma may be deposited on the substrate.When these substances are deposited in the vicinity of the hole, theopening of the hole is blocked, so that etching is not proceeded.Further, even when the opening is not completely blocked, it isdifficult for ions to reach the inside of the hole, and thus, the shapeof the hole is distorted, or etching is not proceeded.

Further, the edge portion of the opening of a mask may be scraped byetching. In this case, as illustrated in FIG. 17C, a phenomenon calledbowing in which the incident direction of ions with respect to the holeis distorted and the shape of the hole is distorted in a barrel shape onthe side wall of the hole may occur.

As described above, in the plasma processing with a high aspect ratio,the processing performance depends on radicals or ions generated inplasma, and reaction products generated by the plasma processing. As aresult, a technology that may individually control, for example,reaction species, radicals, and byproducts in accordance with theprogress of a plasma processing is required.

Embodiment

In embodiments described below, each physical quantity, which is aparameter of a plasma processing, is controlled by applying radiofrequency (RF) power used at the time of plasma generation in a pulseshape. The controlled physical quantities are, for example, ion energy,an ion incident angle, a radical flux, an ion flux, and an amount ofbyproducts.

A plasma processing apparatus according to the embodiment describedbelow is an ICP apparatus. A controller of the plasma processingapparatus of the embodiment controls RF power (source RF signal, sourcepower) supplied to a coil (antenna) by a control signal. In theembodiment, high-density plasma is generated by the supply of a sourceRF signal. The supply of the RF power may be implemented in variousaspects. For example, based on a program prepared in advance, thecontroller of the plasma processing apparatus may switch a power supplypath from a plurality of source RF generators, and sequentially supplythe source power having different power levels in a pulse shape.

A period during which the RF power is supplied to the coil is called anON (operating) period, and a period during which the supply of the RFpower to the coil is stopped is called an OFF (non-operating) period.The source RF signal has a first state corresponding to the ON period,for example, an ON state (source ON state), and a second statecorresponding to the OFF period, for example, an OFF state (source OFFstate). The source RF signal is a pulse signal that forms one cycle(source cycle) constituted by an ON period of the first state and an OFFperiod of the second state that follows. A frequency of the source RFsignal may be approximately 1 kHz to approximately 5 kHz.

The source RF signal of the embodiment may transition in two or morelevels (e.g., first source power level and second source power level) inthe first state. For example, the first state of the source RF signalmay have a first level at which the RF power of a predetermined value issupplied to the coil and a second level at which the RF power of a valuelower than that of the first level is supplied to the coil. For example,the source RF signal may have a first level at which approximately 1,000watts of the RF power is supplied to the coil, and a second level atwhich approximately 250 watts of the RF power is supplied to the coil.The RF power supplied in two levels may be approximately 100 watts orapproximately 150 watts. The first level and the second level may be ahigh level and a low level, respectively.

A controller may further control the RF power (bias RF signal, biaspower) supplied to a lower electrode of the plasma processing apparatusby a control signal. In the embodiment, by the supply of the bias RFsignal, an ionic bond is caused in a substrate placed above the lowerelectrode, and reaction species and radicals are generated. The supplyof the RF power may be implemented in various aspects. For example,based on a program prepared in advance, the controller of the plasmaprocessing apparatus may switch a power supply path from a plurality ofbias RF generators, and sequentially supply the bias power havingdifferent power levels in a pulse shape.

A period during which the RF power is supplied to the lower electrode iscalled an ON period, and a period during which the supply of the RFpower to the lower electrode is stopped is called an OFF period. Thebias RF signal has a first state corresponding to the ON period, forexample, an ON state (bias ON state), and a second state correspondingto the OFF period, for example, an OFF state (bias OFF state). The biasRF signal is a continuous pulse signal that forms one cycle (bias cycle)constituted by an ON period of the first state and an OFF period of thesecond state that follows. A frequency of the bias RF signal may beapproximately 1 kHz to approximately 5 kHz.

The bias RF signal of the embodiment may transition in two or morelevels (e.g., first bias power level and second bias power level) in thefirst state. For example, the first state of the bias RF signal may havea first level at which the RF power of a predetermined value is suppliedto the lower electrode and a second level at which the RF power of avalue lower than that of the first level is supplied to the lowerelectrode. For example, the bias RF signal may have the first level atwhich approximately 250 watts of the RF power is supplied to the lowerelectrode, and the second level at which approximately 92.5 watts of theRF power is supplied to the lower electrode. The first level and thesecond level may be a high level and a low level, respectively.

First, an example of a configuration of the plasma processing apparatusthat executes the plasma processing will be described below.

Example of Configuration of Plasma Processing Apparatus According toEmbodiment

FIG. 1 is a conceptual view of a configuration of a plasma processingapparatus according to an embodiment. FIG. 2 is a schematic verticalcross-sectional view illustrating an example of the configuration of theplasma processing apparatus in FIG. 1 . A plasma processing apparatus 1according to an embodiment will be described with reference to FIGS. 1and 2 . The plasma processing apparatus 1 illustrated in FIG. 2 is aso-called inductively-coupled plasma (ICP) apparatus, and generatesinductively coupled plasma.

The plasma processing apparatus 1 includes a plasma processing chamber10, a gas supply 20, a power supply 30, and an exhaust system 40. Theplasma processing chamber 10 includes a dielectric window 10 a and aside wall 10 b. The dielectric window 10 a and the side wall 10 b definea plasma processing space 10 s in the plasma processing chamber 10.Further, the plasma processing apparatus 1 includes a support 11disposed in the plasma processing space 10 s, an edge ring 12, a gasintroducer 13, and an antenna 14. The support 11 includes a substratesupport 11 a and an edge ring support 11 b. The edge ring support 11 bis disposed to surround an outer peripheral surface of the substratesupport 11 a. The antenna 14 is disposed on or above the plasmaprocessing chamber 10 (dielectric window 10 a).

The substrate support 11 a includes a substrate support area, and isconfigured to support a substrate on the substrate support area. In theembodiment, the substrate support 11 a includes an electrostatic chuckand a lower electrode. The lower electrode is disposed below theelectrostatic chuck. The electrostatic chuck functions as the substratesupport area. Further, although not illustrated, according to theembodiment, the substrate support 11 a may include a temperatureadjusting module configured to adjust at least one of the electrostaticchuck and the substrate to a target temperature. The temperatureadjusting module may include a heater, a flow path, or a combinationthereof. A temperature adjusting fluid such as a coolant or a heattransfer gas flows through the flow path.

The edge ring 12 is disposed to surround a substrate W on the uppersurface of the peripheral edge portion of the lower electrode. The edgering support 11 b includes an edge ring support area, and is configuredto support the edge ring 12 on the edge ring support area.

The gas introducer 13 is configured to supply at least one processinggas from the gas supply 20 to the plasma processing space 10 s. In theembodiment, the gas introducer 13 includes a central gas injector 13 aand/or a side wall gas injector 13 b. The central gas injector 13 a isdisposed above the substrate support 11 a, and is attached to a centralopening formed in the dielectric window 10 a. The side wall gas injector13 b is attached to a plurality of side wall openings formed in the sidewall of the plasma processing chamber 10.

The gas supply 20 may include at least one gas source 21 and at leastone flow rate controller 22. In the embodiment, the gas supply 20 isconfigured to supply one or more processing gases from the correspondinggas sources 21 to the gas introducer 13 via the corresponding flow ratecontrollers 22. Each flow rate controller 22 may include, for example, amass flow controller or a pressure-control type flow rate controller.Further, the gas supply 20 may include one or more flow rate modulationdevices that modulate or pulse the flow rate of one or more processinggases.

The power supply 30 includes an RF power supply 31 coupled to the plasmaprocessing chamber 10. The RF power supply 31 is configured to supply anRF signal (RF power, e.g., source RF signal and bias RF signal) to thelower electrode and the antenna 14. Therefore, plasma is generated fromat least one processing gas supplied to the plasma processing space 10s. In the embodiment, the RF signal is pulsed. Examples of the pulsed RFsignal includes a pulse RF signal, pulse RF power, a pulse source RFsignal and a pulse bias RF signal.

In the embodiment, the RF power supply 31 includes a source RF generator31 a and a bias RF generator 31 b. The source RF generator 31 a and thebias RF generator 31 b are coupled to the plasma processing chamber 10.In the embodiment, the source RF generator 31 a is coupled to theantenna 14, and the bias RF generator 31 b is coupled to the lowerelectrode in the substrate support 11 a. The source RF generator 31 a isconfigured to generate at least one source RF signal. In the embodiment,the source RF signal has a frequency in a range of 27 MHz to 100 MHz.The generated source RF signal is supplied to the antenna 14. The biasRF generator 31 b is configured to generate at least one bias RF signal.The bias RF signal has a frequency lower than that of the source RFsignal. In the embodiment, the bias RF signal has a frequency in a rangeof 400 kHz to 13.56 MHz. The generated bias RF signal is supplied to thelower electrode. Further, in various embodiments, an amplitude of atleast one RF signal of the source RF signal and the bias RF signal maybe pulsed or modulated. The amplitude modulation may include pulsing theRF signal amplitude between an ON state and an OFF state, or between twoor more different ON states.

Further, the power supply 30 may include a DC power supply 32. In theembodiment, the DC power supply 32 is configured to apply at least oneDC voltage to the lower electrode. In the embodiment, at least one DCvoltage may be applied to another electrode such as an electrode in theelectrostatic chuck. In the embodiment, the DC signal may be pulsed.Further, the DC power supply 32 may be provided in addition to the RFpower supply 31, or may be provided instead of the bias RF generator 31b.

The antenna 14 includes one or a plurality of coils (ICP coils). In theembodiment, the antenna 14 may include an outer coil and an inner coildisposed coaxially. In this case, the RF power supply 31 may be coupledto both the outer coil and the inner coil, or may be coupled to any oneof the outer coil and the inner coil. In the former case, the same RFgenerator may be coupled to both the outer coil and the inner coil, orseparate RF generators may be separately coupled to the outer coil andthe inner coil.

The exhaust system 40 may be connected to, for example, an exhaust port(gas outlet) provided in a bottom portion of the plasma processingchamber 10. The exhaust system 40 may include a pressure valve and avacuum pump. The vacuum pump may include a turbo molecular pump, aroughing pump, or a combination thereof.

In the embodiment, the controller (corresponding to a control device 50in FIG. 2 ) processes computer-executable instructions that cause theplasma processing apparatus 1 to execute the various steps described inthe present disclosure. The controller may be configured to control eachelement of the plasma processing apparatus 1 so as to execute thevarious steps described here. In the embodiment, a part of or the entirecontroller may be included in the plasma processing apparatus 1. Thecontroller may include, for example, a computer. The computer mayinclude, for example, a processor (central processing unit: CPU), astorage unit, and a communication interface. The processor may beconfigured to perform various control operations based on a programstored in the storage unit. The storage unit may include a random accessmemory (RAM), a read only memory (ROM), a hard disk drive (HDD), a solidstate drive (SDD), or a combination thereof. The communication interfacemay communicate with the plasma processing apparatus 1 via acommunication line such as a local area network (LAN).

Flow of Plasma Processing According to Embodiment

FIG. 3 is a flowchart illustrating an example of a flow of a plasmaprocessing according to the embodiment. The plasma processingillustrated in FIG. 3 may be performed in the plasma processingapparatus 1 in FIGS. 1 and 2 . FIGS. 4A to 4C are views illustrating anexample of a substrate processed by the plasma processing according tothe embodiment.

First, the substrate W is provided in the plasma processing chamber 10(step S31). For example, as illustrated in FIGS. 4A to 4C, the substrateW includes a base layer L1, an etching target layer (Si layer) L2, and amask MK sequentially formed on a silicon substrate. A recess OP isformed in the substrate W in advance (see FIG. 4A). The formation of therecess OP may be performed in the plasma processing apparatus 1.Subsequently, the plasma processing apparatus 1 is controlled by thecontroller so that the gas for etching is supplied from the gas supply20 into the plasma processing chamber 10. Further, the plasma processingapparatus 1 is controlled by the controller so that the RF power issupplied from the RF power supply 31 (source RF generator 31 a and biasRF generator 31 b) to the lower electrode and the antenna 14 (coil). Atthis time, the RF power supply 31 supplies the RF power at a levelcorresponding to the waveform of the RF signal to the lower electrodeand the antenna 14. The waveform of the RF signal will be describedlater. By supplying the RF power, plasma of the gas supplied into theplasma processing chamber 10 is generated, and plasma etching isexecuted (step S32). By the plasma etching, the bottom portion of therecess OP formed in the mask MK of the substrate W is scraped, and thus,the recess OP gradually becomes deeper (see FIG. 4B). Then, thecontroller of the plasma processing apparatus 1 determines whether apredetermined processing time has elapsed (step S33). When apredetermined processing time has elapsed, the bottom portion of therecess OP reaches the base layer L1, and has the shape illustrated inFIG. 4C. When it is determined that the processing time has not elapsed(No in step S33), the controller returns to step S32 and continues theplasma etching. Meanwhile, when it is determined that the processingtime has elapsed (Yes in step S33), the controller ends the processing.

The plasma processing apparatus 1 according to the embodiment suppliesthe source RF signal and the bias RF signal in the plasma etching instep S32. The plasma processing apparatus 1 controls, for example, ionsand radicals in the plasma, and an amount of the byproducts generated bythe plasma etching according to the source RF signal and the bias RFsignal. Subsequently, the waveforms of the source RF signal and the biasRF signal will be described.

(Waveform Example of RF Signal)

FIG. 5 is a view illustrating a waveform example of the RF signal usedfor RF power supply in the plasma processing according to theembodiment.

A timing diagram 100 illustrated in FIG. 5 illustrates a source power(source RF signal) P_(S) and a bias power (bias RF signal) P_(B). Thesource power P_(S) is RF power supplied from the source RF generator 31a to the antenna (coil) 14. Further, the bias power P_(B) is RF powersupplied from the bias RF generator 31 b to the lower electrode of thesubstrate support 11 a. The source RF generator 31 a generates thesource power P_(S), for example, according to the control signalsupplied from the controller. The generated source power P_(S) issupplied to the coil. The bias RF generator 31 b generates the biaspower P_(B), for example, according to the control signal supplied fromthe controller. The generated bias power P_(B) is supplied to the lowerelectrode.

In FIG. 5 , a cycle 150 indicates one cycle of the source RF signal. Acycle 160 indicates one cycle of the bias RF signal. In the followingdescription, when it is not necessary to particularly distinguish,cycles 150 ₁, 150 ₂, . . . are collectively referred to as the cycle150, and cycles 160 ₁, 160 ₂, . . . are collectively referred to as thecycle 160. One cycle refers to a period from the rise of the pulsesignal to the next rise, that is, the total period of an ON period andan OFF period. The source RF signal and the bias RF signal are pulsesignals having the same frequency.

The source RF signal repeats an ON state (first state) during which theRF power is supplied to the coil, and an OFF state (second state) duringwhich the RF power is not supplied to the coil. When the source RFsignal is the ON state, the source power P_(S) is supplied to the coil.When the source RF signal is the OFF state, the power is not supplied tothe coil, that is, the supply of the RF power to the coil is stopped.

The bias RF signal repeats the ON state (first state) during which theRF power is supplied to the lower electrode, and the OFF state (secondstate) during which the RF power is not supplied to the lower electrode.In the example in FIG. 5 , when the bias RF signal is the ON state, thebias power P_(B) is supplied to the lower electrode. When the bias RFsignal is the OFF state, the power is not supplied to the lowerelectrode, that is, the supply of the RF power to the lower electrode isstopped.

In FIG. 5 , the rise of the bias RF signal is delayed by a period D₁with respect to the rise of the source RF signal. After the source RFsignal has transitioned from an ON state to an OFF state, the bias RFsignal rises while the source RF signal is an OFF state. As describedabove, the timing at which the cycle of the source RF signal is startedand the timing at which the cycle of the bias RF signal is started aredeviated by the period D₁. In the example in FIG. 5 , the transitiontiming from the bias OFF state (t₃) in the preceding bias cycle to thebias ON state P_(BL) (t₃) in the first bias cycle 160 ₁ is delayed withrespect to the transition timing to the source ON state P_(SH) (from 0to t₁) in the first source cycle 150 ₁ corresponding to the first biascycle 160 ₁. Further, as illustrated by t₃ in FIG. 5 , the source OFFperiod partially overlaps with the bias OFF period. Further, asillustrated by t₆ in FIG. 5 , the bias ON period in the first bias cycle160 ₁ partially overlaps with the source ON period in the second sourcecycle 150 ₂.

Further, the respective lengths of the ON period and the OFF period ofthe source RF signal are different from the respective lengths of the ONperiod and the OFF period of the bias RF signal. In the example in FIG.5 , the duty ratio (ratio of the length of the ON period to one cycle)of the source RF signal is approximately 40%. Further, the duty ratio ofthe bias RF signal is approximately 60%. However, the duty ratios of thesource RF signal and the bias RF signal are not limited to the abovevalues. Further, the source RF signal and the bias RF signal may havethe same duty ratio.

As described above, the states of the source RF signal and the bias RFsignal are individually transitioned. The timing of the statetransition, and the power level of the transition source and thetransition destination of the source RF signal may be different from thetiming of the state transition, and the power level of the transitionsource and the transition destination of the bias RF signal.

Further, there are a period T_(OFF) during which both the source RFsignal and the bias RF signal are not supplied, and a period T_(ON)during which both the source RF signal and the bias RF signal aresupplied. The supply aspects of the source power P_(S) and the biaspower P_(B) change in the following five phases.

(1) First Phase (ST₁ in FIG. 5 ):

A first phase is defined by a parameter set {P_(S1), P_(B1), and t₁}.Here, P_(S1) is a value of the source power P_(S) supplied during thefirst phase. P_(B1) is a value of the bias power P_(B) supplied duringthe first phase. t₁ refers to a length of the period of the first phase.Here, the following relationships are established.

P _(S1)>0

P _(B1)>0

t ₁>0

In the first phase, the source power P_(S) having a High power levelP_(SH) (first source power level) is supplied to the coil, and also, thebias power P_(B) having a High power level P_(BH) (second bias powerlevel) is supplied to the lower electrode. During the period t₁ in thefirst phase, the RF power is supplied to each of the upper portion andthe lower portion of the plasma processing apparatus 1 to generateplasma, and ions and radicals are generated in the plasma. During anetching processing, etching is proceeded during the period t₁.

(2) Second Phase (ST₂ in FIG. 5 ):

A second phase is defined by a parameter set {P_(S2), P_(B2), and t₂}.Here, P_(S2) is a value of the source power P_(S) supplied during thesecond phase. P_(B2) is a value of the bias power P_(B) supplied duringthe second phase. t₂ refers to a length of the period of the secondphase. Here, the following relationships are established.

P _(S1) >P _(S2)>0

P _(B2)=0

t ₂>0

In the second phase, the source power P_(S) having a Low power levelP_(SL) (second source power level) is supplied to the coil, and thesupply of the bias power P_(B) is stopped. The second phase is, forexample, a period t₂ in FIG. 5 . During the period t₂, the RF power issupplied to the upper portion of the plasma processing apparatus 1.Since the RF power is not supplied to the lower electrode side, a forcethat draws ions is not generated on the lower electrode side. Further,the amounts of ions and radicals generated are also reduced.

(3) Third Phase (ST₃ in FIG. 5 ):

A third phase is defined by a parameter set {P_(S3), P_(B3), and t₃}.Here, P_(S3) is a value of the source power P_(S) supplied during thethird phase. P_(B3) is a value of the bias power P_(B) supplied duringthe third phase. t₃ refers to the length of the period of the thirdphase. Here, the following relationships are established.

P _(S3) =P _(B3)=0

t ₃>0

In the third phase, the supply of both the source power P_(S) and thebias power P_(B) is stopped. The third phase is, for example, a periodt₃ in FIG. 5 . During the period t₃, the plasma generation in the plasmaprocessing apparatus 1 is stopped and the plasma processing space 10 sis exhausted by the function of the exhaust system 40. At this time,byproducts that are generated by etching and are staying at the bottomportion of the recess (OP in FIGS. 4A to 4C) are exhausted. The amountsof ions and radicals in the plasma processing space 10 s are alsoreduced.

(4) Fourth Phase (ST₄ in FIG. 5 ):

A fourth phase is defined by a parameter set {P_(S4), P_(B4), and t₄}.Here, P_(S4) is a value of the source power P_(S) supplied during thefourth phase. P_(B4) is a value of the bias power P_(B) supplied duringthe fourth phase. t₄ refers to a length of the period of the fourthphase. Here, the following relationships are established.

P _(S4)=0

P _(B1) >P _(B4)>0

t ₄>0

In the fourth phase, the supply of the bias power P_(B) having a Lowpower level P_(BL) (first bias power level) is started while the supplyof the source power P_(S) is stopped. Since the source power P_(S) isnot supplied during the period t₄ in the fourth phase, plasma is notgenerated, but the ions generated in the first and the second phasesremain in the plasma processing space 10 s. As a result, the ions aredrawn to the bottom portion of the recess (OP in FIGS. 4A to 4C) by thesupply of the bias power P_(B). Further, the incident angle of the ionsbecomes closer to vertical, and the vertical etching of the recess OPside wall is promoted.

(5) Fifth Phase (ST₅ in FIG. 5 ):

A fifth phase is defined by a parameter set {P_(S5), P_(B5), and t₅}.Here, P_(S5) is a value of the source power P_(S) supplied during thefifth phase. P_(B5) is a value of the bias power P_(B) supplied duringthe fifth phase. t₅ refers to a length of the period of the fifth phase.Here, the following relationships are established.

P _(S5)=0

P _(B1) =P _(B5) >P _(B4)>0

t ₅>0

In the fifth phase, the power level of the bias power P_(B) rises(transitions) from the Low power level P_(BL) to the High power levelP_(BH) while the supply of the source power P_(S) is stopped. As aresult, as a preparing step for the first phase, the ion energy in theplasma processing space 10 s increases in the fifth phase. The amount ofradicals or byproducts is maintained at the reduced state in the thirdphase.

After the fifth phase, the processing returns to the first phase, andthe source power P_(S) having the High power level and the bias powerP_(B) having the High power level are superimposed and applied. Thesecycles are repeated, the first phase is started in a state where ionenergy is generated in advance by applying the bias power P_(B) in thefifth phase, and ions and radicals are generated by applying the sourcepower P_(S). As a result, the etching in the first phase may bepromoted, and ions may be drawn to the bottom portion of the recess OPmore efficiently. Further, the etching may further be promoted byexhausting the byproducts in the third phase.

As described above, by using the source RF signal and the bias RF signalhaving the pulse waveform in FIG. 5 , the etching in the verticaldirection may be implemented while controlling the states of the ions,the radicals, and the byproducts in the plasma processing space 10 s. Asa result, the processing performance of the plasm etching may beimproved by suppressing the shape abnormality occurred by etching.

However, in the example in FIG. 5 , the source power P_(S) takes thevalue P_(SH) when the period t₁ is an ON state, and takes the valueP_(SL) when the following period t₂ is an ON state. Further, the biaspower P_(B) takes the value P_(BL) during the period t₄, and transitionsto the value P_(BH) in the subsequent period t₅. As described above, inthe plasma processing method according to the embodiment, in order tocontrol each physical quantity of plasma, the ON state of the source RFsignal may be controlled in two levels (three levels including an OFFstate). Further, in the plasma processing method according to theembodiment, the ON state of the bias RF signal may be controlled in twolevels (three levels including an OFF state). As described above, it ispossible to further finely adjust parameters of the plasma processing bygradually varying the RF power value applied to each of the coil and thelower electrode.

In the example in FIG. 5 , the following relationships are established.

0<P _(SL) <P _(SH)

0<P _(BL) <P _(BH)

Frequency of source RF signal and bias RF signal: 0.1 kHz to 5 kHz

Duty ratio of source RF signal:approximately 40%

Duty ratio of bias RF signal:approximately 60%

Length of period of P_(SH):Length of period of P_(SL)=1:3

Length of period of P_(BH):Length of period of P_(BL)=1:2

t₁:t₂:t₃:t₄:t₅=1:3:1:4:1

However, the embodiment may be applied not only when the aboverelationships are established, but also to other relationships. Otherrelationships will be described later as a modification.

FIGS. 6A to 6E to 9A to 9E are views for explaining changes of physicalquantities in the plasma processing chamber 10 according to a waveformexample of the RF signal. The changes of the physical quantitiesaccording to the waveform of the RF signal will be described withreference to FIGS. 6A to 6E to 9A to 9E.

Waveform Example 1 in FIGS. 6A to 6E has a “first phase” in which thesource power and the bias power are supplied at the same time, a “secondphase” in which the source power is supplied, and a “fourth phase” inwhich the bias power is supplied. Comparing to the waveform example inthe above embodiment, Waveform Example 1 is different in that it doesnot have a “third phase” in which the RF power is not supplied, and a“fifth phase” in which the power level of the bias power varies beforethe rise of the source RF signal. In the case of Waveform Example 1, allof the ion flux, the radical flux, and the ion energy increase in thefirst phase, and the amount of the byproduct increases at the same time.Thereafter, all amounts gradually decrease in the second phase. The ionenergy becomes substantially zero by stopping the supply of the biaspower. In the fourth phase, the ion energy becomes larger than that inthe first phase due to the supply of the bias power. Meanwhile, theamounts of the ion flux, the radical flux, and the byproduct are notsignificantly changed from the second phase.

Waveform Example 2 in FIGS. 7A to 7E is substantially the same asWaveform Example 1 in FIGS. 6A to 6E. However, a value P_(BM) of thebias power in the fourth phase increases from the value P_(BL) of thebias power in Waveform Example 1. In the example in FIGS. 7A to 7E, theamounts of the ion flux, the radical flux, and the byproduct aresubstantially the same as the case of Waveform Example 1 in FIGS. 6A to6E. However, the ion energy in the fourth phase is increased as comparedwith Waveform Example 1 (C1 in FIG. 7D). In FIG. 7D, the change of theion energy in the case of FIG. 7A is illustrated on the same broken linein FIG. 6D by a thick broken line C1 only in a portion different fromFIG. 6D.

In Waveform Example 3 in FIGS. 8A to 8E, the first phase is lengthenedas compared with Waveform Example 1 in FIGS. 6A to 6E, and the secondphase is shortened by that amount. In the example in FIGS. 8A to 8E, theamounts of the ion flux and the radical flux are increased as comparedwith the example in FIGS. 6A to 6E through the first phase and thesecond phase (C2 and C3 in FIGS. 8B and 8C). Meanwhile, the amounts ofthe ion energy and the byproduct are not largely changed. The thickbroken lines C2 and C3 indicate the portion different from FIGS. 6B and6C, similar to the thick broken line C1.

As compared with Waveform Example 1 in FIGS. 6A to 6E, Waveform Example4 in FIGS. 9A to 9E is different in that the fifth phase is provided.The power level in the fifth phase transitions from the power levelP_(BL) in the fourth phase to the power level P_(BH). In the example inFIGS. 9A to 9E, the amounts of the ion flux, the radical flux, and thebyproduct are substantially the same as those of Waveform Example 1 inFIGS. 6A to 6E. With respect to the ion energy, it is increased in thefifth phase corresponding to the switching of the bias power P_(B) inthe fifth phase (C4 in FIG. 9D). The thick broken line C4 in FIG. 9Dindicates the portion different from FIG. 6D.

When etching is performed using the RF power in the waveform examplesillustrated in FIGS. 6A to 6E to 9A to 9E, in Waveform Example 1 andWaveform Example 3, the variation in the dimension (critical dimension)from the top of the recess to the bottom portion of the recess increasesas compared with Waveform Example 2. That is, as in the fourth phase inWaveform Example 2, when the bias power having a slightly high level issupplied, a hole having a more uniform size in the longitudinaldirection may be formed during deep hole etching. Meanwhile, when theratio of the length of the first phase and the length of the secondphase as in Waveform Example 3, the consumption of the mask is reduced,and the etching target film may be selectively etched. From this aspect,it may be found that the state of ions or radicals in the plasmaprocessing space 10 s, particularly in the vicinity of the substrate,which is a processing target, is changed according to the waveform ofthe RF power, which affects the performance of the plasma processing. Asa result, the performance of the plasma processing, that is, the shapeof the pattern formed by the plasma processing may be controlled byadjusting the waveform of the RF signal.

Waveform Examples 1 to 4 in FIGS. 6A to 6E to 9A to 9E do not have thethird phase of the embodiment, that is, the phase in which the RF poweris not supplied to either the coil or the lower electrode. Byintroducing the third phase in which the RF power is not supplied, theamount of the byproduct in the plasma processing space 10 s may befurther decreased, and the etching accuracy in the vertical directionmay be improved.

However, the embodiment is not limited to the waveform in FIG. 5 , andthe same effect may be obtained by modifications. In the following,modifications 1 to 5 will be described with reference to FIGS. 10 to 14.

[Modification 1]

FIG. 10 is a view illustrating a waveform example of the RF signal usedfor RF power supply in the plasma processing according toModification 1. A timing diagram 200 illustrated in FIG. 10 illustratesthe source power P_(S) and the bias power P_(B). First, when the periodt₁ is started, the source power P_(SH) and the bias power P_(BH) areapplied. The source power P_(SH) and the bias power P_(BH) aresuperimposed and applied at a constant level through the period t₁.Next, when the period t₃ is reached, the supply of both the source powerP_(S) and the bias power P_(B) is stopped (period T_(OFF)). Next, whenthe period t₄ is reached, the supply of the bias power P_(BH) isstarted. Then, when the timing of the next cycle 150 ₂ is reached, thesupply of the source power P_(SH) is started, and the source powerP_(SH) and the bias power P_(BH) are superimposed and applied (periodT_(ON)).

Unlike the waveform example in FIG. 5 , in the timing diagram 200 inFIG. 10 , the second phase, that is, a phase in which the supply of thesource power P_(S) is continued, and the supply of the bias power P_(B)is stopped does not exist. Further, the timing diagram 200 in FIG. 10does not have the fifth phase, that is, a phase in which the level ofthe bias power P_(B) is changed before the supply of the source powerP_(S). As a result, Modification 1 may be applied to a case of patternformation suitable for starting the exhaust of byproducts (third phase)without adjusting the amount of ions or radicals. Further, Modification1 may be applied to a case where it is not necessary to generate ionenergy before generating plasma.

[Modification 2]

FIG. 11 is a view illustrating a waveform example of the RF signal usedfor RF power supply in the plasma processing according to Modification2. First, in a timing diagram 210 illustrated in FIG. 11 , in the periodt₁, the source power P_(SH) and the bias power P_(BH) are applied. Inthe next period t₂, the level of the source power P_(S) is changed fromP_(SH) to P_(SM). Further, when the period t₂ is started, the supply ofthe bias power P_(BH) is stopped. Next, when the period t₃ is reached,the supply of the source power P_(SM) is stopped. As a result, duringthe period t₃, both the source power P_(S) and the bias power P_(B) arenot supplied (period T_(OFF)). Then, when the period t₄ is reached, thesupply of the bias power P_(BM) is started. During the period t₄, thebias power P_(B) at the level P_(BM) is supplied. Then, when the periodt₅ is reached, the level of the bias power P_(B) is changed from P_(BM)to P_(BH). Then, when the next cycle 150 ₂ is reached while the supplyof the bias power P_(BH) is continued, the source power P_(SH) issupplied, and the source power P_(SH) and the bias power P_(BH) aresuperimposed and supplied (period T_(ON)).

Comparing to the waveform example in FIG. 5 , Modification 2 isdifferent in that the level of the source power P_(S) is set P_(SH) andP_(SM). The level of the source power P_(S) is set from a high level toa low level in the order of the levels P_(SH), P_(SM), and P_(SL).Further, Modification 2 is different from the waveform example in FIG. 5in that the level of the bias power P_(B) is set P_(BH) and P_(BM). Thelevel of the bias power P_(B) is set from a high level to a low level inthe order of the levels P_(BH), P_(BM), and P_(BL). In the case ofModification 2, ON states of the source power P_(S) and the bias powerP_(B) are set two levels. However, the lower level of the two levels isset to be a level higher than the case of the example in FIG. 5 .

For example, when it is required to maintain, for example, electrondensity Ne, radical density Nr, electron temperature Te, and ion energysi at a high level before and after the third phase in which byproductsare exhausted, the levels of a plurality of ON states of the sourcepower P_(S) and the bias power P_(B) may be set to be high similar toModification 2.

Also in Modification 2, as in the waveform example in FIG. 5 , the riseof the bias RF signal is delayed by the period D₁ from the rise of thesource RF signal. Further, the period T_(OFF) in which both the sourcepower P_(S) and the bias power P_(B) are not supplied exists. Further,the period T_(ON) in which both the source power P_(S) and the biaspower P_(B) are supplied exists. The period T_(ON) is a period from thetiming at which the source RF signal is raised to the timing at whichthe bias RF signal is fallen.

[Modification 3]

FIG. 12 is a view illustrating a waveform example of the RF signal usedfor RF power supply in the plasma processing according to Modification3. First, in a timing diagram 220 illustrated in FIG. 12 , in the periodt₁, the source power P_(SH) and the bias power P_(BM) are supplied.Next, in the period t₂, the level of the source power P_(S) is changedfrom P_(SH) to P_(SM). Further, when the period t₂ is reached, thesupply of the bias power P_(BM) is stopped. Next, when the period t₃ isreached, the supply of the source power P_(SM) is stopped. During theperiod t₃, both the source power P_(S) and the bias power P_(B) are notsupplied (period T_(OFF)). Then, in the period t₄, the supply of thebias power P_(BH) is started. During the period t₄, the bias power P_(B)at the level P_(BH) is supplied. Then, when the period t₅ is reached,the level of the bias power P_(B) is changed from P_(BH) to P_(BM).Then, when the cycle 150 ₂ is started while the supply of the bias powerP_(BM) is continued, the source power P_(SH) is supplied, and the sourcepower P_(SH) and the bias power P_(BM) are superimposed and supplied(period T_(ON)).

Modification 3 is substantially the same as Modification 2 in FIG. 11 .However, Modification 3 is different from Modification 2 in thetransition order of the levels of the bias power P_(B). In Modification2, the levels of the bias power P_(B) are P_(BH) during the period t₁,P_(BM) during the period t₄, and P_(BH) during the period t₅. Withregard to this, in Modification 3, the levels of the bias power P_(B)are P_(BM) during the period t₁, P_(BH) during the period t₄, and P_(BM)during the period t₅. In Modification 2, the level of the bias powerP_(B) is changed in the order of the high level, the OFF state, the lowlevel, and the high level from the first phase to the fifth phase. Withregard to this, in Modification 3, the level of the bias power P_(B) ischanged in the order of the low level, OFF state, the high level, andthe low level from the first phase to the fifth phase.

For example, the waveform of Modification 3 is suitable for, forexample, a case of the plasma processing suitable for drawing ions tothe bottom portion of the recess OP by increasing ion energy in thethird phase.

[Modification 4]

FIG. 13 is a view illustrating a waveform example of the RF signal usedfor RF power supply in the plasma processing according to Modification4. First, in a timing diagram 230 illustrated in FIG. 13 , in the periodt₁, the source power P_(SM) and the bias power P_(BH) are applied. Next,in the period t₂, the level of the source power P_(S) is changed fromP_(SM) to P_(SH). Further, when the period t₂ is reached, the supply ofthe bias power P_(BH) is stopped. Next, in the period t₃, the supply ofthe source power P_(SH) is stopped. During the period t₃, both thesource power P_(S) and the bias power P_(B) are not supplied (periodT_(OFF)). Then, in the period t₄, the supply of the bias power P_(BM) isstarted. During the period t₄, the bias power P_(B) at the level P_(BM)is supplied. Then, when the period t₅ is reached, the level of the biaspower P_(B) is changed from P_(BM) to P_(BH). Then, when the next cycle150 ₂ is reached while the supply of the bias power P_(BH) is continued,the source power P_(SM) is supplied, and the source power P_(SM) and thebias power P_(BH) are superimposed and supplied (period T_(ON)).

Modification 4 is substantially the same as Modification 2 in FIG. 11 .However, Modification 4 is different from Modification 2 in thetransition order of the levels of the source power P_(S). InModification 2, the levels of the source power P_(S) is P_(SH) duringthe period t₁, and P_(SM) during the period t₂. With regard to this, inModification 4, the levels of the source power P_(S) is P_(SM) duringthe period t₁, and P_(SH) during the period t₂. In Modification 2, thelevel of the source power P_(S) is changed in the order of high, low,and OFF from the first phase to the third phase, and is not changed fromthe third phase to the fourth phase. With regard to this, inModification 4, the level of the source power P_(S) is changed in theorder of low, high, and OFF from the first phase to the third phase, andis not changed from the third phase to the fourth phase.

Modification 4 is suitable for, for example, a processing required togradually increase the amounts of ions and radicals instead of rapidlyincreasing the amounts of ions and radicals in the first phase.

[Modification 5]

FIG. 14 is a view illustrating a waveform example of the RF signal usedfor RF power supply in the plasma processing according to Modification5. First, in a timing diagram 240 illustrated in FIG. 14 , in the periodt₁, the source power P_(SM) and the bias power P_(BM) are applied. Next,when the period t₂ is reached, the level of the source power P_(S) ischanged from P_(SM) to P_(SH). Further, when the period t₂ is reached,the supply of the bias power P_(BM) is stopped. Next, when the period t₃is reached, the supply of the source power P_(SH) is stopped. During theperiod t₃, both the source power P_(S) and the bias power P_(B) are notsupplied (period T_(OFF)). Then, when the period t₄ is reached, thesupply of the bias power P_(BH) is started. During the period t₄, thebias power P_(B) at the level P_(BH) is supplied. Then, when the periodt₅ is reached, the level of the bias power P_(B) is changed from P_(BH)to P_(BM). Then, when the next cycle 150 ₂ is reached while the supplyof the bias power P_(BM) is continued, the source power P_(SM) issupplied, and the source power P_(SM) and the bias power P_(BM) aresuperimposed and supplied (period T_(ON)).

Modification 5 is a waveform obtained by combining the bias power P_(B)of Modification 3 in FIG. 12 and the source power P_(S) of Modification4 in FIG. 13 . The bias power P_(B) of Modification 3 is changed in theorder of the low level (first phase), the OFF state (second and thirdphases), the high level (fourth phase), and the low level (fifth phase)from the first phase to the fifth phase. Further, the source power P_(S)of Modification 4 is changed in the order of the low level (firstphase), the high level (second phase), and the OFF state (third to fifthphases) from the first phase to the fifth phase. As a result, in thewaveform of Modification 5, {P_(S), P_(B)} is changed in the order of{P_(SM), P_(BM)}, {P_(SH), P_(BOFF)}, {P_(SOFF), P_(BOFF)}, {P_(SOFF),P_(BH)}, and {P_(BOFF), P_(BM)} from the first phase to the fifth phase.Here, when the ON state has two levels in one waveform, one is called ahigh level, and the other is called a low level, and any level is calleda middle level. Further, the OFF state of the source power P_(S) isindicated by P_(SOFF), and the OFF state of the bias power P_(B) isindicated by P_(BOFF).

Modification 5 is suitable for, for example, a processing required toetch after raising ion energy once and then lowering the ion energy inthe fourth phase.

(Flow of RF Power Supply)

FIG. 15 is a flowchart illustrating an example of a flow of the RF powersupply of the plasma processing according to the embodiment. A flow 1500illustrated in FIG. 15 is executed in step S32 in FIG. 3 .

First, the RF power supply 31 executes the RF power supply in the firstphase under the control of the controller (step S1510). The RF powersupply in the first phase is defined by a first set processing parameter{P_(S1), P_(B1), and t₁}. Here, P_(S1)>0, P_(B1)>0, and t₁>0.

Next, the RF power supply 31 executes the RF power supply in the secondphase under the control of the controller (step S1520). The RF powersupply in the second phase is defined by a second set processingparameter {P_(S2), P_(B2), and t₂}. Here, P_(S2)>0, P_(B2)=0, and t₂≥0.

Next, the RF power supply 31 executes the RF power supply in the thirdphase under the control of the controller (step S1530). The RF powersupply in the third phase is defined by a third set processing parameter{P_(S3), P_(B3), and t₃}. Here, P_(S3)=0, P_(B3)=0, and t₃>0.

Next, the RF power supply 31 executes the RF power supply in the fourthphase under the control of the controller (step S1540). The RF powersupply in the fourth phase is defined by a fourth set processingparameter {P_(S4), P_(B4), and t₄}. Here, P_(S4)=0, P_(B4)>0, and t₄>0.

Next, the RF power supply 31 executes the RF power supply in the fifthphase under the control of the controller (step S1550). The RF powersupply in the fifth phase is defined by a fifth set processing parameter{P_(S5), P_(B5), and t₅}. Here, P_(S5)=0, P_(B5)>0, and t₅≥0.

Steps S1510 to S1540 are executed as one cycle. After step S1540, theprocessing may return to step S1510 continuously, and the cycle may beexecuted again.

FIG. 16 is a flowchart illustrating another example of the flow of theRF power supply of the plasma processing according to the embodiment. Aflow 1600 illustrated in FIG. 16 is executed in step S32 in FIG. 3 .

First, the RF power supply 31 supplies the source power P_(S) to theantenna (coil) 14, and supplies the bias power P_(B) to the lowerelectrode at the same time under the control of the controller.Therefore, plasma is generated in the plasma processing space 10 s.Further, the plasma includes ions and radicals (step S1610).

Next, the RF power supply 31 stops the supply of the bias power P_(B) tothe lower electrode under the control of the controller. Further, the RFpower supply 31 changes the value of the source power P_(S) supplied tothe antenna (coil) 14. For example, the RF power supply 31 decreases orincreases the source power P_(S). Therefore, the RF power supply 31adjust the amounts of the ions and the radicals included in the plasmain the plasma processing space 10 s (step S1620).

Next, under the control of the controller, the RF power supply 31 stopsthe supply of the source power P_(S) to the coil while the supply of thebias power P_(B) to the lower electrode is stopped. Then, the amount ofthe byproduct in the plasma processing space 10 s is decreased by theexhaust processing of the plasma processing space 10 s by the exhaustsystem 40 (step S1630).

Next, the RF power supply 31 supplies bias power P_(B) to the lowerelectrode under the control of the controller. The supply of the sourcepower P_(S) remains stopped. A drawing force to the lower electrode bythe bias power P_(B) is generated (step S1640).

Steps S1610 to S1640 are executed as one cycle. After step S1640, theprocessing may return to step S1510 continuously, and the cycle may beexecuted again.

A part of the above embodiment and Modifications may be appropriatelymodified. Considered modified aspects are disclosed in the following.

Other Embodiment

The source power P_(S) may be alternating current (AC) power. Further,the source power P_(S) may be radio frequency (RF) power or very highfrequency (VHF) power. The source power P_(S) may be, for example, RFpower in a range of approximately 60 MHz to approximately 200 MHz.Further, the source power P_(S) may be, for example, RF power in a rangeof approximately 25 MHz to approximately 60 MHz. The source power P_(S)may be, for example, 27 MHz. In the embodiment, the source power P_(S)generates inductively coupled plasma (ICP). For example, the sourcepower P_(S) combines with a helical antenna to generate plasma.

The bias power P_(B) may be alternating current (AC) power. Further, thebias power P_(B) may be direct current (DC) pulse power. The bias powerP_(B) may be any one of radio frequency (RF) power, high frequency (HF)power, and medium frequency (MF) power. The bias power P_(B) may be, forexample, power having a frequency in a range of approximately 200 kHz toapproximately 600 kHz. The bias power P_(B) may be, for example, 400kHz. Further, the bias power P_(B) may be, for example, power in a rangeof approximately 600 kHz to approximately 13 MHz.

The source power P_(S) and the bias power P_(B) may be applied as asingle pulse or as a continuous pulse in each cycle, respectively. Forexample, in the first phase, the source power P_(S1) applied in theperiod t₁ may be a single pulse or a continuous pulse. In the samemanner, the bias power P_(B2) applied in the period t₂ may be a singlepulse or a continuous pulse.

The duty ratios of the source RF signal and the bias RF signal may beindividually set in a range of approximately 3% to approximately 90%.

For example, in a case of a three-level waveform, the duty ratio of theON state at a high level of the source RF signal may be set in a rangeof approximately 5% to approximately 50%. Further, the duty ratio of theON state at a low level of the source RF signal may be set in a range ofapproximately 0% to approximately 45%. Further, the duty ratio of theOFF state of the source RF signal may be set in a range of approximately5% to approximately 90%.

Further, the duty ratio of the ON state at a high level of the bias RFsignal may be set in a range of approximately 5% to approximately 50%.Further, the duty ratio of the ON state at a low level of the bias RFsignal may be set in a range of approximately 0% to approximately 45%.Further, the duty ratio of the OFF state of the bias RF signal may beset in a range of approximately 5% to approximately 90%.

Further, the length of the period during which the source RF signal andthe bias EF signal are OFF states at the same time may be set in a rangeof the duty ratio of approximately 5% to approximately 90%. This periodmay be set, for example, in a range of approximately 0 microseconds toapproximately 500 microseconds, and further, in a range of approximately10 microseconds to approximately 50 milliseconds. Further, in thisperiod, the duty ratios of the source RF signal and the bias RF signalmay be set in a range of approximately 10% to approximately 50%.

A gas is supplied to the plasma processing chamber 10 at a flow rateselected according to a predetermined plasma processing. The gas issupplied to the plasma processing chamber 10 at substantially the sameflow rate during one cycle including the first phase, the second phase,the third phase, the fourth phase, and the fifth phase. The supplied gasincludes, for example, hydrogen bromide (HBr). Further, the supplied gasincludes, for example, a rare gas such as helium (He) or argon (Ar).Further, the supplied gas may include, for example, oxygen (O₂),tetrafluoromethane (CF₄), nitrogen trifluoride (NF₃), sulfurhexafluoride (SF₆), chlorine (Cl₂), and tetrachloromethane (CCl₄).

The byproduct generated during the plasma processing according to theembodiment may be a compound containing the gas in the plasma processingchamber 10 and one or more kinds of elements contained in thecomposition of the substrate. For example, when a silicon substrate andHBR gas are used, the byproduct containing SiBrx may be produced.Additionally, for example, silicon-containing residues such as siliconfluoride (SiFx) or silicon chloride (SiClx), or carbon-containingresidues such as fluorocarbon (CFx) or hydrofluorocarbon (CHxFy) (in acase of a processing using a photoresist, an organic film, or aprecursor) may be produced as a byproduct.

Effect of Embodiment

As described above, the plasma processing apparatus according to theembodiment includes the plasma processing chamber, the substratesupport, the source RF generator, and the bias RF generator. Thesubstrate support is disposed in the plasma processing chamber. Thesource RF generator is coupled to the plasma processing chamber, and isconfigured to generate a pulse source RF signal including a plurality ofsource cycles. Each source cycle has a source operating state during asource operating period and a source non-operating state during a sourcenon-operating period after the source operating period. The bias RFgenerator is coupled to the substrate support, and is configured togenerate a pulse bias RF signal. The pulse bias RF signal has aplurality of bias cycles having the same pulse frequency as theplurality of source cycles. Each bias cycle has a bias operating stateduring a bias operating period and a bias non-operating state during abias non-operating period after the bias operating period. A transitiontiming to the bias operating state in each bias cycle is delayed withrespect to a transition timing to the source operating state in thecorresponding source cycle. The source OFF period overlaps with the biasnon-operating period. The bias operating period in each bias cycleoverlaps with the source operating period in the next source cycle. Asdescribed above, the plasma processing apparatus supplies the RF signalso that the cycles of the pulse source RF signal and the pulse biassignal are deviated. Further, the plasma processing apparatus suppliesthe RF signal so that the bias operating period lasts over two cycles ofthe pulse source RF signal. As a result, the plasma processing apparatusmay improve the performance of the plasma etching by finely controlling,for example, ion energy generated during the plasma etching. Further,the source operating period and the bias operating period are deviated,and thus, the plasma processing apparatus may set the power levelsupplied at the rise (at the start of the cycle) of the pulse source RFsignal to be high. As a result, the plasma processing apparatus mayimplement efficient plasma etching.

As described above, in the plasma processing apparatus according to theembodiment, the source operating state may have at least two sourcepower levels. Further, the bias operating state may have at least twobias power levels.

As described above, in the plasma processing apparatus according to theembodiment, the source operating state may have a first source powerlevel and a second source power level after the first source powerlevel. The bias operating state may have a first bias power level and asecond bias power level after the first bias power level. The pulse biasRF signal may transition to the bias operating state during the sourcenon-operating period in each source cycle.

As described above, in the plasma processing apparatus according to theembodiment, the bias RF signal may transition from the first bias powerlevel to the second bias power level during the source non-operatingperiod in each source cycle.

As described above, in the plasma processing apparatus according to theembodiment, a transition from the first source power level to the secondsource power level in each source cycle may be substantiallysynchronized with a transition from the bias operating state to the biasnon-operating state in each bias cycle.

As described above, in the plasma processing apparatus according to theembodiment, the first source power level may be larger than the secondsource power level.

As described above, in the plasma processing apparatus according to theembodiment, the first source power level may be smaller than the secondsource power level.

As described above, in the plasma processing apparatus according to theembodiment, the second bias power level may be larger than the firstbias power level.

As described above, in the plasma processing apparatus according to theembodiment, the second bias power level may be smaller than the firstbias power level.

Further, the plasma processing method according to the embodiment may bea plasma processing method used in a plasma processing apparatus. Theplasma processing apparatus may include a plasma processing chamber, anantenna, a first RF generator, a substrate support, and a second RFgenerator. The antenna may be disposed above the plasma processingchamber. The first RF generator may be coupled to the antenna andgenerate a first RF power. The substrate support may be disposed in theplasma processing chamber. The second RF generator may be coupled to thesubstrate support and generate a second RF power. The plasma processingmethod may include supplying the first RF power to the antenna andsupplying the second RF power to the substrate support in a firstperiod. Further, the plasma processing method may include supplying thefirst RF power to the antenna and stopping the supply of the second RFpower to the substrate support in a second period after the firstperiod. Further, the plasma processing method may include stopping thesupply of the first RF power to the antenna and stopping the supply ofthe second RF power to the substrate support in a third period after thesecond period. Further, the plasma processing method may includesupplying the second RF power to the substrate support without supplyingthe RF power to the antenna in a fourth period after the third period.Then, the plasma processing method may repeatedly execute each step.

It should be considered that the embodiments disclosed in here areexemplary and not restrictive in all aspects. The above-describedembodiments may be omitted, replaced, or changed in various formswithout departing from the scope of claims and the gist thereof. Forexample, in the above embodiments, the plasma processing method executedusing an inductively-coupled plasma apparatus has been described as anexample. However, the disclosed technology is not limited thereto, andmay also be applied to a plasma processing method using another plasmaprocessing apparatus. For example, a capacitively-coupled plasma (CCP)apparatus may be used instead of an inductively-coupled plasmaapparatus. In this case, the capacitively-coupled plasma apparatusincludes two facing electrodes disposed in the plasma processingchamber. In the embodiment, one electrode is disposed in the substratesupport, and the other electrode is disposed above the substratesupport. In this case, one electrode functions as a lower electrode, andthe other electrode functions as an upper electrode. Then, the source RFgenerator 31 a and the bias RF generator 31 b are coupled to at leastone of the two facing electrodes. In the embodiment, the source RFgenerator 31 a is coupled to the upper electrode, and the bias RFgenerator 31 b is coupled to the lower electrode. The source RFgenerator 31 a and the bias RF generator 31 b may be coupled to thelower electrode.

According to the present disclosure, the processing performance of theplasma etching may be improved.

From the foregoing, it will be appreciated that various embodiments ofthe present disclosure have been described herein for purposes ofillustration, and that various Modifications may be made withoutdeparting from the scope and spirit of the present disclosure.Accordingly, the various embodiments disclosed herein are not intendedto be limiting, with the true scope and spirit being indicated by thefollowing claims.

What is claimed is:
 1. A method for processing a substrate comprising:providing a plasma processing apparatus including a chamber, a substratesupport disposed in the chamber, a lower electrode disposed in thesubstrate support, and an antenna disposed above the chamber; supplyinga pulsed source RF signal to the antenna, the pulsed source RF signalincluding a plurality of source cycles, each source cycle having asource operating state during a source operating period and a sourcenon-operating state during a source non-operating period after thesource operating period; and supplying a pulsed bias RF signal to thelower electrode, the pulsed bias RF signal including a plurality of biascycles having a same pulse frequency as that of the plurality of sourcecycles, each bias cycle having a bias operating state during a biasoperating period and a bias non-operating state during a biasnon-operating period after the bias operating period, wherein atransition timing to the bias operating state in each bias cycle isdelayed with respect to a transition timing to the source operatingstate in a corresponding source cycle, the source non-operating periodoverlaps with the bias non-operating period, and the bias operatingperiod in each bias cycle overlaps with the source operating period in anext source cycle.
 2. The method according to claim 1, wherein thesource operating state has at least two source power levels, and thebias operating state has at least two bias power levels.
 3. The methodaccording to claim 2, wherein the source operating state has a firstsource power level and a second source power level after the firstsource power level, the bias operating state has a first bias powerlevel and a second bias power level after the first bias power level,and the pulsed bias RF signal transitions to the bias operating stateduring the source non-operating period in each source cycle.
 4. Themethod according to claim 3, wherein the pulsed bias RF signaltransitions from the first bias power level to the second bias powerlevel during the source non-operating period in each source cycle. 5.The method according to claim 4, wherein a transition from the firstsource power level to the second source power level in each source cycleis substantially synchronized with a transition from the bias operatingstate to the bias non-operating state in each bias cycle.
 6. The methodaccording to claim 5, wherein the first source power level is greaterthan the second source power level.
 7. The method according to claim 5,wherein the first source power level is less than the second sourcepower level.
 8. The method according to claim 7, wherein the second biaspower level is greater than the first bias power level.
 9. The methodaccording to claim 7, wherein the second bias power level is less thanthe first bias power level.
 10. The method according to claim 3, whereina transition from the first source power level to the second sourcepower level in each source cycle is substantially synchronized with atransition from the bias operating state to the bias non-operating statein each bias cycle.
 11. The method according to claim 3, wherein thefirst source power level is greater than the second source power level.12. The method according to claim 3, wherein the first source powerlevel is less than the second source power level.
 13. The methodaccording to claim 3, wherein the second bias power level is greaterthan the first bias power level.
 14. The method according to claim 3,wherein the second bias power level is less than the first bias powerlevel.
 15. A method for processing a substrate comprising: providing aplasma processing apparatus including a chamber, a substrate supportdisposed in the chamber, a lower electrode disposed in the substratesupport, and an upper electrode disposed above the substrate support;supplying a pulsed source RF signal to the upper electrode or the lowerelectrode, the pulsed source RF signal including a plurality of sourcecycles, each source cycle having a source operating state during asource operating period and a source non-operating state during a sourcenon-operating period after the source operating period; and supplying apulsed bias RF signal to the lower electrode, the pulsed bias RF signalincluding a plurality of bias cycles having a same pulse frequency asthat of the plurality of source cycles, each bias cycle having a biasoperating state during a bias operating period and a bias non-operatingstate during a bias non-operating period after the bias operatingperiod, wherein a transition timing to the bias operating state in eachbias cycle is delayed with respect to a transition timing to the sourceoperating state in a corresponding source cycle, the sourcenon-operating period overlaps with the bias non-operating period, andthe bias operating period in each bias cycle overlaps with the sourceoperating period in a next source cycle.
 16. The method according toclaim 15, wherein the source operating state has at least two sourcepower levels, and the bias operating state has at least two bias powerlevels.
 17. The method according to claim 16, wherein the sourceoperating state has a first source power level and a second source powerlevel after the first source power level, the bias operating state has afirst bias power level and a second bias power level after the firstbias power level, and the pulsed bias RF signal transitions to the biasoperating state during the source non-operating period in each sourcecycle.
 18. The method according to claim 17, wherein the pulsed bias RFsignal transitions from the first bias power level to the second biaspower level during the source non-operating period in each source cycle.19. The method according to claim 18, wherein a transition from thefirst source power level to the second source power level in each sourcecycle is substantially synchronized with a transition from the biasoperating state to the bias non-operating state in each bias cycle. 20.The method according to claim 17, wherein a transition from the firstsource power level to the second source power level in each source cycleis substantially synchronized with a transition from the bias operatingstate to the bias non-operating state in each bias cycle.